title: Obstructive sleep apnea is associated with preserved bone mineral density in healthy elderly subjects.
abstract: OBJECTIVE
  Chronic intermittent hypoxia (IH) acts as a stimulator of mesenchymal stem cell (MSC) mobilization, intensifying osteoblast formation in animal models. The recurrence of apnea and oxygen desaturation in obstructive sleep apnea (OSA) may mimic experimental models of IH. We hypothesized that in elderly with OSA, apnea-related IH may mobilize MSCs and thereby prevent the age-related decline in osteogenesis. This study explored the relationship between OSA and bone mineral density (BMD), and the effect of IH on BMD, in a large sample of elderly subjects.
  
  
  METHODS
  There were 833 volunteers age 68.6 ± 0.8 y (59% women).
  
  
  METHODS
  Each participant underwent evaluation of BMD at lumbar spine and femoral sites by dual-energy x-ray absorptiometry (DEXA) as well as clinical and polygraphic examinations. OSA was diagnosed on the basis of an apnea-hypopnea index (AHI) ≥ 15.
  
  
  RESULTS
  There were 55% of the participants who presented with OSA, and these subjects were predominantly male and overweight. Compared with subjects without OSA, those with OSA had a higher femoral and spinal BMD (P < 0.001). Body mass index (BMI), AHI, and oxygen desaturation index (ODI) (P < 0.01) were significantly related to BMD. After adjustment for sex, BMI, metabolic values, and hypertension, multiple regression analysis showed a significant association between femoral and lumbar T scores and both daily energy expenditure (P < 0.001) and ODI (P = 0.007).
  
  
  CONCLUSIONS
  In elderly subjects, the presence of obstructive sleep apnea is associated with higher bone mineral density, with oxygen desaturation index being a significant determinant of bone metabolism. These results suggest that apnea-related intermittent hypoxia may stimulate the bone remodeling process in older population.
  
  
  BACKGROUND
  NCT 00759304 and NCT 00766584.
authors.affiliation: Service de Physiologie Clinique et de l'Exercice, CHU Nord, Saint-Etienne, Faculté de Médecine Jacques Lisfranc, PRES de Lyon 42023,Université Jean Monnet, Saint-Etienne, France.
authors.forename: Emilia
authors.initials: E
authors.lastname: Sforza
authors.forename: Thierry
authors.initials: T
authors.lastname: Thomas
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Barthélémy
authors.forename: Philippe
authors.initials: P
authors.lastname: Collet
authors.forename: Frédéric
authors.initials: F
authors.lastname: Roche
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D015519:Bone Density / Q000502:physiology*; D001842:Bone and Bones / Q000378:metabolism; D016022:Case-Control Studies; D005260:Female; D005269:Femur / Q000502:physiology; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology; D008297:Male; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000378:metabolism / Q000503:physiopathology*
keywords: Bone mineral density; intermittent hypoxia; obstructive sleep apnea; osteogenesis; osteoporosis